The voltage regulator on an outboard boat motor basically does what the name says. Voltage, supplied from the power generation of the flywheel and the stator is regulated to the appropriate level output of about 13.6 volts to the battery. The voltage regulator on most newer and larger outboard boat motors also contains a rectifier which job is to convert the AC current of the flywheel/stator generation to DC output (which only flows one direction) for the battery charging requirement. The rectifier also converts the tach output of the stator so that a tachometer can recieve the correct pulse type and display rpm of the motor correctly. Due to the location of a voltage regulator in the outboard ignition system, it can be treated rather roughly so to speak. For example, having a big output stator such as 40 amps, can really put a load on the regulator which can develop a very high heat issue. Some regulators are air cooled, while others are water cooled. With a water cooled type regulator, a faulty or weak water pump can cause a regulator to burn out from excessive heat buildup. There have actually been cases where water cooled regulators have gotten so hot, it catches fire and creates a very serious safety concern. A bad or excessively low charged battery can also cause the regulator to overheat and burnt out. Since the regulator has a direct connection to the stator, the stator can also result with damage when the regulator burns up and shorts out. In ending, if your outboard boat motor has a water cooled regulator, make sure the water pump is always in good working order, and always make sure your battery is in good condition as well.